Grinding machine

Abstract

A grinding machine comprising a tool mounting head which is movable vertically between a pair of guide columns on which guide surfaces are provided for guiding the head. A plurality of workpieces are mounted on corresponding holding jigs which are mounted by means enabling them to be tilted, and measurement means such as X-ray or optical means are provided to sense the orientation of a workpiece being machined, with signals from the measurement means controlling the tilting of the corresponding holding jig. Jigs are mounted on a rotary table rotatably mounted on a workpiece slide which can be traversed below a grinding tool.

What is claimed is: 
     
       1. A grinding machine, comprising a bed;   a pair of guide columns fixedly mounted on said bed, with a plurality of guide surfaces being formed on said guide columns in a common vertical plane;   a tool mounting head disposed between said guide columns, supported for vertical movement by supporting means comprising elevating means coupled to said tool mounting head and operable to adjust the vertical position of said tool mounting head, sensing and control means for detecting any vertically directed force applied to said elevation means by said tool mounting head, and an operating member coupled to support said tool mounting head and controlled by said sensing and control means for applying a vertically directed force to said tool mounting head having a direction and magnitude such as to compensate for said vertically directed force applied to said elevation means by said tool mounting head, said tool mounting head being further provided with hydrostatic bearing means for restraining said tool mounting head against movement other than in a direction parallel to said plane of said guide surfaces of the guide columns;   a tool shaft rotatably mounted in said tool mounting head;   drive means for rotating said tool shaft;   a grinding tool fixedly mounted on said tool shaft;   a workpiece slide mounted on said bed for sliding motion traversing a guide surface formed on said bed; and   means for mounting at least one workpiece holding jig upon said workpiece slide.   
     
     
       2. A grinding machine according to claim 1, in which said elevating means comprise: an electric motor fixedly mounted with respect to said bed, and;   a vertically oriented elevating screw shaft engaging in a threaded bore formed in said tool mounting head and coupled to be rotated by said motor to thereby selectively raise and lower said tool mounting head;   and in which said sensing and control means comprise:   a flange formed on said elevating screw shaft, provided with upper and lower horizontal surfaces;   upper and lower pressure chambers filled with hydraulic fluid and disposed to enclose said upper and lower surfaces of the flange respectively;   sensor means for sensing the pressures within said upper and lower pressure chambers respectively and for producing output signals indicative of a difference between said pressures, and;   hydraulic actuator means controlled by said output signals from said sensor means;   and in which said operating member comprises an operating rod coupled to said hydraulic actuator means and attached to said tool mounting head, actuated by said hydraulic actuator means to apply forces to said tool mounting head selectively directed upward and downward in accordance with said output signals from said sensor means such as to equalize said pressures in said upper and lower pressure chambers; whereby the weight of said tool mounting head is effectively supported by said operating rod and whereby the vertical position of said tool mounting head is accurately determined by an amount of rotation of said elevating screw shaft.